Update the Tempfile.open spec to confirm the options argument is passed to File.open.
Update the Tempfile.open spec to confirm the options argument is passed
to File.open.

This spec is in response to jruby/jruby#5456

ruby/rubyspec,ruby/spec,nobu/rubyspec,ruby/spec,eregon/rubyspec,ruby/rubyspec,eregon/rubyspec,nobu/rubyspec,eregon/rubyspec,ruby/spec,nobu/rubyspec